Patent GB-989227-A (GB)
Title: Control mechanism for a driving unit consisting of a driving engine and an infinitely variable speed gear
IPC: F02D29/02
Filed: 1961-08-03
Abstract: 989,227. Variable-speed control. W. REIMERS. Aug. 3, 1961 [Aug. 4, 1960], No. 28195/61. Heading F2D. [Also in Division G3] In a control system for a continuously variable speed gear 1 wherein a force dependent upon gear ratio and/or output load is necessary to maintain and/or vary at will the gear ratio, and the force is produced by an hydraulic or pneumatic servo supplied through a valve b jointly controlled through a floating lever 25 by the position of the gear adjusting element and by a hand lever e, means dependent upon engine condition are provided to reduce the force and thus the gear ratio when the maximum admissable engine load is exceeded. As shown applied to an expanding pulley gear 1 fluid-pressure servos a, d respectively connected to the movable flanges 6, 7 of each pulley are supplied with pressure liquid from a pump 10 through the valve b, the spool of which is connected to the floating lever 25 and has lands 14, 15 which control the admission of fluid-pressure to and exhaust from the servos a, d. One end 26 of the lever 25 is pivotally connected to the movable flange 7 of the driven pulley whilst the other end 28 is connected to the hand lever e. For ratio shift rotation of the lever e moves the valve spool 20 to the left or right whereupon increased liquid pressure is supplied through line 22 or 23 to servo d or a whilst the pressure in the other servo is reduced. Unintentional ratio shift due to an increase or decrease in output load is compensated for by the rightward or leftward movement of flange 7 which acts through lever 25 to move the valve spool 20 right or left and thus decrease or increase the pressure in servo d whilst increasing or decreasing the pressure in servo a to restore the selected ratio. When the maximum admissable engine load is exceeded the gear ratio is automatically reduced by opening a normally closed valve f which reduces system pressure by providing restricted communication at 46 between supply line 11 and an exhaust line 21. The spool 41 of valve f is mechanically connected to the engine fuel rack 40. The supply line 11 is provided with a pressure relief valve 44 and a manually operable valve 52 cuts out ratio reduction on excess engine load. In Figs. 2-4 (not shown) on excess engine load a valve between the servo a and exhaust line 21 is opened to reduce the liquid pressure in servo a and hence the gear ratio. In Fig. 2 (not shown) the valve is operated by an engine suction servo. In Fig. 3 (not shown) the valve is operated by liquid pressure from the pump 10 controlled by an additional valve connected to the engine fuel rack. In Fig. 4 (not shown) the valve is operated by an electromagnet the circuit of which is completed by a switch connected to the engine fuel rack. In Fig. 5 (not shown) system pressure is reduced on excess engine load by a pressure relief valve which is normally closed by system pressure acting through a spring on the valve. The pressure acting on the valve is controlled by an additional valve connected to the engine fuel rack. In Figs. 6 and 7 (not shown) the gear ratio is reduced on excess engine load by a servo in, or acting on, the linkage between the hand lever e and floating lever 25, which servo is energized under the control of a valve fast with the engine fuel rack to move valve spool 20 to a position to reduce the gear ratio. In Fig. 8 (not shown) the expanding pulley gear is replaced by any other type of continuously variable speed gear in which it is necessary that a force dependant upon the gear ratio and/or output load acts on the adjusting member to maintain or vary at will the gear ratio. The adjusting member of the gear is acted upon by a servo piston which is also connected to one end of the lever 25. The servo is supplied with pressure liquid from the pump 10 through the valve b which controls the pressures acting on each side of the servo piston. Specification 934,798 is referred to.